AP Physics 1 : Impulse and Momentum

Study concepts, example questions & explanations for AP Physics 1

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Example Questions

Example Question #41 : Impulse And Momentum

Deep in space Object has mass and is initially traveling with velocity .  At , it collides with Object , which has mass and is initially motionless. The two objects stick together.

Determine the initial momentum of the system.

Possible Answers:

Impossible to determine

None of these

Correct answer:

Explanation:

Using

Plugging in values:

Example Question #42 : Impulse And Momentum

Deep in space Object has mass and is initially traveling with velocity .  At , it collides with Object , which has mass and is initially motionless. The two objects stick together.

Determine the impulse experienced by Object

Possible Answers:

None of these

Correct answer:

Explanation:

Using

Plugging in values:

The momentum will be the same in the final state, so again using

Solving for velocity:

Plugging in values (the total mass is equal to the combined masses:

Definition of impulse:

Example Question #42 : Impulse And Momentum

A ball of mass is thrown at a target. The ball strikes with a velocity of and bounces back with equal magnitude. Determine the magnitude of impulse experienced by the ball.

Possible Answers:

Correct answer:

Explanation:

Impulse is defined as change in momentum:

Using

Combining equations:

Plugging in values:

Example Question #43 : Impulse And Momentum

Frictionless cart is traveling at when it hits identical frictionless cart which was previously motionless. After the collision, cart is traveling at . Determine the final velocity of cart .

Possible Answers:

None of these

Correct answer:

Explanation:

Using conservation of momentum:

Solving for

Using (since the carts are identical):

Plugging in values:

Example Question #45 : Impulse And Momentum

During time period , a rocket ship deep in space of mass travels from to . During time period , the rocket fires. During time period , the rocket travels from  to .

Time periods , and all took

Determine the impulse during time period .

Possible Answers:

None of these

Correct answer:

Explanation:

Finding initial momentum:

Combining equations:

Plugging in values:

Combining equations:

Converting to and plugging in values:

Using

Plugging in values:

Example Question #231 : Linear Motion And Momentum

Ty throws a  snowball directly at his brother who also throws a snowball directly at Ty with a mass of , because he dipped it in a bucket of water. Ty throws his snowball at  and his brother throws his at  and the two snowballs make perfect contact in mid flight, causing a perfectly inelastic collision. Neglecting air resistance, what is the combined final speed of the snowballs and their direction following the collision?

Possible Answers:

; negative x-direction

; positive x-direction

; positive x-direction

; negative x-direction

Correct answer:

; negative x-direction

Explanation:

Use the conservation of momentum for inelastic collisions (objects that stick together).

Plug in and solve for the final velocity.

The final velocity of the combined snowballs is  in the negative x-direction.

Example Question #232 : Linear Motion And Momentum

On a toy car set, two children apply a piece of double sided tape to the front of two toy cars so that when they collide they will stick together causing a perfectly inelastic collision. The two identical cars have a combined mass of  and their final combined speed was  in the rightward direction. If car "A" was shot to the right with a speed measured at  right before the collision . At what speed was the other car traveling right before the collision?

Possible Answers:

Correct answer:

Explanation:

Use the conservation of momentum, perfectly inelastic collision.

Plug in and solve for the speed of car B.

The velocity of car B right before the collision was .

Example Question #233 : Linear Motion And Momentum

A spaceship is stationary deep in space with it’s rocket broken. The crew decides to propel it to earth by throwing tennis balls out the back window. If they throw one tennis ball every second at , how many balls will it take the ship to reach ? Each tennis ball has a mass of  and the ship has a mass of .

Possible Answers:

None of these

Correct answer:

Explanation:

The net momentum of the system needs to stay constant, that is, any momentum given to the tennis balls, the space ship must gain in the opposite direction.

Where

is the mass of the ship.

is the velocity of the ship

is the number of balls thrown

is the mass of a ball

is the velocity of a thrown ball

Solving for 

Since the velocities are given as magnitudes, the negative sign can be ignored

Plugging in values

Example Question #234 : Linear Motion And Momentum

A bullet with mass  is shot with an initial kinetic energy of . What was the impulse on the bullet as it was fired?

Possible Answers:

Correct answer:

Explanation:

The expression for impulse is the following:

We are given mass and initial kinetic energy, so we can also calculate the velocity of the bullet. Therefore, we will go with the second for of the expression:

Finding an expression for velocity, we get:

Rearranging for velocity, we get:

Plugging this in, we get:

Plugging in our values, we get:

Example Question #235 : Linear Motion And Momentum

A bullet of mass  is shot at a velocity of  and an angle of  above the horizontal. What is the momentum of the bullet at its maximum height? Neglect air resistance.

Possible Answers:

Correct answer:

Explanation:

When the bullet is at its maximum height, it has no vertical velocity component. Also, since we are neglecting air resistance, the horizontal velocity remains constant. Therefore, the velocity of the bullet at its maximum height is simply the initial horizontal velocity:

Plugging in values, we get:

Then using the expression for momentum:

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